Machining DataSheet for

General Information:
Material GroupK - Cast Iron
Sub-GroupCast Iron
Hardness220.0 HB
Tensile Strength730 [N/mm^2]

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Machining Cast Iron GG25

GG25 is a Grey cast iron material with a Machinability rating of 112% and Hardness 220 HB.

Grey cast Iron is the most britle cast iron sub-group. It is the easiest to machine and produces tiny chips even when using a flat insert without a chip breaker

In Cast Iron, the material standards also define the allowed hardness range, and hardness is the top-ranking factor affecting the machinability ratings. For example, nodular cast iron is known to be harder to machine compared with grey cast iron. However, if a grey cast iron alloy has a hardness of 300HB is will have lower machinability than nodular cast iron with 200HB.

Cast iron is very brittle and produces short chips. Therefore there is no need for a sharp cutting edge, and a strong geometry with a large honing or K-land is the best choice.


  • For general Turning of Cast Iron GG25 at stable conditions use a grade with a Very Hard substrate and CVD coating.
  • In case you are running at a cutting speed that is lower than 490 SFM (150 m/min), it is better to use a grade with a
  • Very Hard substrate and PVD coating.
  • For general Milling use a grade with a Semi Hard substrate and CVD coating.
  • For detailed carbide grades recommendations, check the Below Chart, or use the Grades Wizrad.
  • Recommended Cutting speed range for turning at stable conditions is 720 - 970 [SFM] / 220 - 295 [m/min].
  • Consider using CBN inserts. Although they cost more than twice, they enable increasing the cutting speed by 2-4 times (relative to carbide). Learn More ⇒
  • Recommended Cutting speed range for milling with stable clamping and short overhang is 490 - 660 [SFM] / 150 - 200 [m/min]
  • For detailed cutting speed recomendations, check the Below Table, or use our Speed and Feed Calculator.

  • Equivalent International Designations for Cast Iron GG25

    Standard Name
    bsGrade 250

    Chemical Composition for Cast Iron GG25

    Sorry, Not Availble for this Material

    Cutting Speeds Recomendations for Cast Iron GG25

    * Click on the speeds below for higher precision in specific conditions!

    ApplicationVc (m/min)Vc (SFM)

    Important! The speed estimation is given for an ideal situation:

    • Most suitable carbide grade
    • Stable tool clamping
    • Stable workpiece clamping
    • Good quality raw material
    • A short overhang of the cutting tool.
    • Nominal hardness of the material.
    • etc.
    Click on the speeds in the above table to get better precision for specific parameters
    Or use our Speed and Feed Calculator

    Recommended Carbide Grades for Cast Iron GG25

    * If you do nott understand the below table? Read This Explanation to make the most out of it!

    Grade for Turning

    Grade for Parting Off

    Grade for Grooving

    Grade for Milling (Indexable)

    Recommended Insert Cutting Edge Geometry for Cast Iron GG25

    Honing Size:0.05-0.10 mm / 0.002-0.004"
    Rake Angle:0° -0°
    Land Angle:Negative
    Land Width:0.30-0.40 mm / 0.012-0.016"

    Learn more about carbide inserts Cutting-Edge Geometry Parameters.

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